Slight Water Damage in Ceiling, Vapor Barrier?

[DKAudio]

Hey everyone, MN climate if that matters.

I had a roof leak around my furnace exhaust a few years ago. The leak was fixed but a small area of my ceiling in the dining room needs repair. I am going to scrape the entire ceiling clean (remove popcorn texture) and use a roughly 2'x2' piece of drywall as replacement. I am just wondering, is a vapor barrier needed between the blow in insulation in the attic and the paper of the drywall back or can I just screw the replacement piece right to the joists?

[pushkins]

If there is none there now then putting a piece 2'x2' in now is pointless.

[DKAudio]

I believe there is some; it is thin black paper like material, asphalt composition perhaps? Anyways, I just used some plastic, tucked it under the black paper, placed the blow in insulation on top and called it good. The piece ended up being 32”x20” so not a huge repair.

General question, do new installations just use a plastic material and staple it to the underside of the joists before putting the drywall up?

[pushkins]

All installations or remodels are required to have faced insulation, in cases where loose/blow in insulation is used, felt paper (roofing felt) like you have or plastic is stapled to the underside of the ceiling joists before drywall is hung. Foam insulation is in itself a vapor barrier so no other vapor barrier is required.
The caveat here is that faced insulation or vapor barriers are only required with insulation that borders "conditioned" rooms for example exterior walls (obviously) and say a garage ceiling that has a heated or cooled living space above. Even with the garage walls insulated (most are not) and an insulated garage door vapor barriers are still required because of the air exchange every time that door is opened. interior walls like between bedrooms can be insulated but with un faced insulation, all your really doing is adding a level of sound barrier.

[Adamblake33]

I think if the leaky roof was repaired then you won't need a vapor barrier.
Roof leaks cause lots of problems that's for sure.